I've seen a rola bola--and even played on one--but never knew the name.
emanuela:
it is a board-- a plank of wood, about 1 meter long, and a foot -(-20 to30 milimeters?) wide.
(such planks can be bought at lumber building supply stores-- or scavenged from a building site) )
on one (underside) side there are small piece of wood at each about 10 x10 centimeters--and as long as the board is wide. each piece is about 10 to 15 millimeters for the end-
(I'd call then cleats-- the same word used for the metal pegs on "football" or golf shoes)
(i tried to do a diagram with characters-- but it kept messing up..)
the board is balanced on a large metal cylinder-- almost like a small see-saw (teeter-totter)
To use it, you stand on the board, and balance.. as you get good, you can roll back and forth.

the wood on the underside keeps you from rolling off the cylinder. the cylinder could be made of old cans-- the smaller the cylinder, the easier it is.. a good size is about 10--15 millimeters/diameter.

you could make the cylinder from recycled food cans.. Two large tomato cans (.75 kilo size) over wrapped with a sheet of tin, or just taped together with the all purpose american tool--duct tape
(I hope i got the measurements right--i still think in inches, and ounces--i mean the 28 oz. cans of tomatoes.

My work issued ruler is in inches only--at home i have both-- but the exact size is not too important-- about half a body lenght long, and wide enough to be able to stand on.. the cleats positioned so when resting, the edge of the board touches the ground..)

Kids made them themselves...



my other obsession